bch(m4): ABLA replay + dynamic per-tip template size budget (M4 anchor) - #120
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Net-new BCH-specific validation slice (M1 §4.3, no btc/ analogue). CalculateASERT + GetNextASERTWorkRequired ported byte-exact from BCHN src/pow.cpp; anchors from chainparams.cpp (main/testnet3/testnet4). Governs SPV header-accept target only — PoW hash stays SHA256d, zero share-format / p2pool-merged-v36 surface change. Syntax-clean -std=c++20.
Port src/impl/btc/coin/header_chain.hpp to BCH: same store/sync/persistence and SHA256d PoW, with the one BCH divergence being difficulty. Replaces Bitcoin's 2016-block 2-week retarget with ASERT (aserti3-2d) by wiring validate_difficulty()/get_next_work_required() to asert.hpp (slice 18a). - BCHChainParams carries the ASERTParams anchor (asert.hpp) instead of a (timespan, spacing, interval) tuple; pow_limit/allow_min_difficulty mirror the anchor. mainnet/testnet3 genesis shared with Bitcoin (pre-fork); BCH testnet4 genesis flagged TODO-verify against VM300 bchn-bch chainparams. - validate_difficulty drops the ancestor-walk lookback (ASERT is anchor- absolute): trusts pre-anchor history and synthetic checkpoint seeds, else asserts header.nBits == get_next_work_required_asert(tip,...). - No p2pool-merged-v36 surface: ASERT governs header accept only, not the PoW hash or share format. Single-coin, src-only (no impl_bch CMake registration). Syntax-clean -std=c++20. Push held pending PR #106 ratification.
Standalone-parent commitment layout (BTC minus AuxPoW segment): [BIP34 height][/c2pool/][state_root 32B][TheMetadata]. BIP34 enforced per BCHN ContextualCheckBlock; no witness commitment (SegWit struck); CTOR handled separately by template tx sort; CashTokens transparent. Source-only header; shared by M4 GBT builder and the share validator.
…e 1)
Flesh out bch::coin::TemplateBuilder (was an M4 TODO stub) into a working
GBT assembler from HeaderChain + Mempool, mirroring the BTC builder with the
BCH consensus divergences:
* SHA256d merkle root + 50-BCH/210k-halving subsidy (== BTC curve).
* Next-block bits from the ASERT (aserti3-2d) DAA, not a 2016-block
retarget; falls back to tip bits / pow_limit below the ASERT anchor.
* CTOR (CHIP-2018-11): block body re-sorted to ascending txid after fee
selection, coinbase excluded.
* No SegWit: single canonical tx serialization, hash == txid, empty
segwit-free rules array. CashTokens carried transparently in tx bytes.
* EmbeddedCoinNode wired to build_template() for getwork().
Coinbase tx (and its s19 commitment) is still assembled downstream, as on
BTC; binding ../coinbase_commitment.hpp into the coinbase builder is the
next M4 slice. ABLA dynamic block-size and the rules array are pinned to
pre-ABLA 32 MB EB / empty here pending verification vs VM300 bchn-bch GBT
and the p2pool-merged-v36 python reference.
Source-only, -fsyntax-only clean. No impl_bch CMake registration (does not
race ci-steward); bch lane stays skip-green.
…sourcing
Add abla.hpp -- a 1:1 fixed-point port of BCHN consensus/abla.{h,cpp}
(pinned at v29.0.0): Config (MakeDefault/SetMax) + State (NextBlockState,
GetBlockSizeLimit). Mainnet grows; testnets fixed at 32 MB.
Route the template builder block-size byte budget through abla at the
activation/floor limit (32 MB) instead of a static constant. The floor is a
safe LOCAL build cap -- ABLA only ever raises it, so a template built to the
floor can never exceed the live consensus limit. Per-tip ABLA state replay
through the header chain (dynamic limit) is the next size-slice.
No p2pool-merged-v36 surface: ABLA governs only the block-size limit, not
PoW hash, share format, coinbase commitment, or PPLNS math.
Roundtrip exec: floor==32MB both nets; mainnet->41.3MB after 5000 full
blocks; testnet fixed. abla.hpp + template_builder.hpp -fsyntax-only OK.
Add abla::replay() -- replay ABLA State forward from a known-good anchor over a contiguous run of full-block sizes (1:1 BCHN State::NextBlockState loop). Wire TemplateBuilder::build_template to consume an optional caller- supplied per-tip ABLA State, using its GetBlockSizeLimit() as the dynamic block-size budget; absent it, fall back to the activation/floor limit (unchanged, always-safe LOCAL build cap). The per-block-size feed that drives replay is a full-block/embedded-daemon concern (M5+): the headers-only SPV header_chain structurally does not carry block sizes, so the dynamic limit is re-homed there rather than forced into the header chain. Build budget only -- zero p2pool-merged-v36 surface (no PoW hash, share format, coinbase commitment, or PPLNS touched). Validated: mainnet replay 5000x32MB grows 32->39.48MB (bounded by MAX_CONSENSUS_BLOCK_SIZE); testnet fixedSize stays 32MB; empty replay = anchor.
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M4 anchor for the BCH embedded lane. BCH-only: every changed path is under src/impl/bch/ (+ bch tests + .github/workflows/build.yml target registration). Verified zero changes to other coin trees or shared src/core / src/impl/bitcoin_family.
6 commits on top of master (1040ede):
CI: all 6 coin smokes + bch embedded smoke green on the branch. Merge stays operator-gated.